People who have exercised for years, even those who remain obese, store body fat in a healthier way than their inactive peers.
Researchers at the University of Michigan took two groups of adults who had obesity – one group who worked out at least four times a week for two years and one who did not exercise regularly.
The team then took samples of belly fat tissue from both groups and measured the amount of blood flow, markers of inflammation, and the rigidity and fibrousness of the tissue.
Results showed those who exercised had more blood vessels in that tissue, which implied they had a better flow of oxygen throughout their body.
The fat was also less rigid and prone to inflammation, despite both groups having the same percentage of bodyfat, suggesting exercise reduces the negative health effects of being obese.
Two groups of people had similar fat masses, but the group who exercised regularly for years saw better heart health and insulin regulation, leading to better overall health
Lead author Dr Jeffrey Hotowitz, an exercise scientist at the University of Michigan, said: ‘Fat is really misunderstood.’
He added: ‘Our findings indicate that in addition to being a means to expend calories, exercising regularly for several months to years seems to modify your fat tissue in ways that allows you to store your body fat more healthfully if or when you do experience some weight gain – as nearly everyone does as we get older.’
Dr Horowitz continued: ‘We generally see these differences are more robust in people who exercise regularly for years versus those who don’t exercise.’
Their research was published in the journal Nature Metabolism.
The researchers found via blood testing, MRIs and samples of fat tissue examined in the lab, that despite having the same body fat mass and weight, regular exercisers had better heart health.
Their bodies were also more effective at regulating insulin levels, potentially staving off diabetes linked to obesity.
Blood testing revealed regular exercisers tended to have a higher level of ‘good’ HDL cholesterol.
Blood tests also showed frequent exercisers had fewer markers of inflammation in the body and better liver function than their sedentary counterparts.
Regular exercise was also found to reduce the size of fat cells and increase their ability to store and release energy. It reduces the amount of visceral fat a person has as well, reducing the risks of myriad chronic health issues.
The study subjects had subcutaneous fat, according to researchers, who did not look at the more dangerous visceral fat.
Researchers specifically studied subcutaneous fat in 32 people – 16 who exercised four times a week for an average of 11 years and 16 people who led sedentary lives
That’s not to say that subcutaneous fat isn’t dangerous. Too much of it can lead to serious health issues, including diabetes, heart disease, high blood pressure, joint pain, sleep apnea, and fatty liver disease.
Excess belly fat can also cause fat tissue to become denser, disrupting the normal function of fat in the body. Fat stores energy for later use, produces hormones, and regulates metabolism.
Frequent exercisers also had less of a type of collagen most closely associated with problems concerning metabolism, including type 2 diabetes, obesity, an abnormally high amount of fat in the blood, an overactive thyroid gland, and non-alcoholic fatty liver disease.
In people with obesity, the size of fat cells also affects the number of blood vessels in fat tissue that carry oxygen to tissue elsewhere in the body.
Large fat cells often lead to fewer blood vessels in fat tissue, which can reduce the supply of oxygen getting there, cause inflammation, and possible scarring.
While the fat cells in both groups were similar in size, the exercisers had more blood vessels in their fat tissue, suggesting that regular exercise improves the fat tissue’s ability to receive oxygen and nutrients.
This is not the first study to show that exercise can increase blood vessel growth, but scientists have yet to reach a consensus on how many weeks or months of exercise are needed to see a noticeable increase in blood vessels in fat tissue in overweight or obese people.
The UM study offers valuable insight, though it may be disheartening for people with obesity who are just beginning their fitness journey and want quicker results.
